Work feeding mechanism for a centerless grinder



Nov. 10, 1959 A. w. TODD ETAL 2,911,763

WORK FEEDING MECHANISM FOR A CENTERLESS GRINDER Filed Jan. 10, 1957 5 Sheets-Sheet 1 AT TOPNEVS Nov. 10, 1959 A. w. TODD ETAL WORK FEEDING MECHANISM FOR A CENTERLESS GRINDER 5 Sheets-Sheet 2 Filed Jan. 1.0. 1957 .llllll PEEJJY/EE INVENTOPS ALEXANDER W TODD HENRY/ KWAP/E/V 9 a ATTORNEYS Nov. 10, 1959 A. w. TODD ETAL 2,911,763

WORK FEEDING MECHANISM FOR A CENTERLESS GRINDER Filed Jan. 10, 1957 5 Sheets-Sheet 3 INVENTORS ALEXANDER W TODD HENRY P KWAP/EN B aw/9 W amw/ A T TORNEYS Nov. 10, 1959 A. w. TODD ETAL 2,911,763

WORK FEEDING MECHANISM FOR A CENTERLESS GRINDER 5 Sheets-Sheet 4 Filed Jan. 10, 1957 //v VENTORS ALEXANDER m TODD HENRY KWAP/EN 4M4 ATTORNEYS WORK FEEDING MECHANISM FOR A CENTERLESS GRINDER Filed Jan. 10. 195"! Nov. 10, 1959 A. w. TODD ETAL 5 Sheets-Sheet 5 0 W N .A R l5!!! 2 EWW 0 0 v VRK. T m W F I. Z A N I w u a mi&\:/ w H 7% V/m "I!!! i a 6 v H 1 W M M ""l"fl1 U v 5 .I W H M W m 0W 0 x w 9 w W w G J, 4 d D H m y M United States Patent WORK FEEDING MECHANISM FOR A CENTERLESS GRINDER Alexander W. Todd, Springfield, and Henry P. Kwapien, Westfield, Masa, assignors, by mesne assignments, to Van Norman Industries, Inc., Springfield, Mass., a corporation of Massachusetts Application January '10, 1957, Serial No. 633,426

4 Claims. (Cl. 51103) This invention relates to a centerless grinder and, more specifically, to mechanism for handling and particularly for feeding work to a centerless grinder.

It is the general object of the invention to provide a work feeding mechanism for a centerless grinder which is adapted to feed work automatically at the full capacity of the grinder whereby to avoid the time consuming delays experienced in hand feeding work during a production operation.

The drawings show preferred embodiments of the invention and such embodiments will be described, but it will be understood that various changes may be made from the constructions disclosed and that the drawings and description are not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings,

Fig. 1 is an elevational view of a first embodiment of work feeding means provided in accordance with this invention, the view being taken from the position of the regulating Wheel and facing the grinding wheel wherein the front of the machine is on the left;

Fig. 2 is a vertical sectional view taken as indicated by the line 22 of Fig. 1;

Fig. 3 is a slightly enlarged view of the rotatable receiver which takes the workpieces from a magazine in sequence and drops them on the work supporting blade, this view being taken similarly to Fig. l;

Fig. 4 is a vertical sectional view taken as indicated by the line 4--4 of Fig. 3;

Figs. 5 to 8 are detail vertical sectional views of the end of the feed magazine showing a feeding cycle in sequence; V i

Fig. 9 is a plan View of the work ejecting mechanism associated with the regulating wheel; i

Fig. 10 is a front elevational view of the structure shown in Fig. 9; i

Fig. 11 is a diagram of a pneumatic and electrical control system which may be employed with the first embodiment of work feeding means and the work,.l l means;

Fig. 12 is an elevational view of a second embodiment or alternative form of work feeding means providedin accordance with this invention, the view being taken from the position of the grinding wheel and facing the regulating wheel wherein the front of the machine is on the right;

Fig. 13 is a vertical sectionalview taken as indicated by the line 1'3-13 of Fig. 12; i i

Fig. 14 is an enlarged vertical sectional view taken as indicated by the line 1414 of Fig. 12;

Figs. 15 to 18 are detail vertical sectional views of the end of the feed magazine of the second embodiment showing a feeding cycle in sequence;

Fig. 19 is a diagram of a pneumatic and electrical control system which may be employed in the second ,embodiment.

.to provide free running clearance therefor.

Patented Nov. 10, 1959 It should be understood at the outset that a work feeding mechanism for a centerless grinder provided in accordance with the present invention is adapted particu larly for in-feed operation of the grinder wherein a plurality of workpieces are to be fed in sequence for high capacity production operation. The work feeding mechanism can be described generally as comprising a' magazine for carrying the workpieces and which is arranged to gravity feed. the workpieces into the grinding throat between the grinding wheel and regulating wheel of a centerless grinder. The mechanism also includes a re ceiver which is supported for rotation or oscillation on a substantially horizontal axis through approximately The receiver is located below the magazine and is constructed and arranged to receive the lowermost workpiece in the magazine in one rotated position and to drop the said lowermost workpiece from the magazine onto the work supporting blade in another rotated position. In all rotated positions of the receiver, it prevents indiscriminate and undesirable fallout of the workpieces from the magazine. While apparently many different mechanisms. can be provided for rotating or oscillating the receiver in the work feeding process, the said receiver is preferably operated by a pneumatically operated'rack and pinion, the pneumatic operation being timed to the grinding cycle. i

' In any form provided, the work feeding mechanism of this invention is preferably supported upon the work rest or upon the Work rest slide whereby the entire mechanism 'is movable with the work rest relative to the bed of the machine. In the first embodiment of the invention as shown in Fig. 1, the usual work rest is indicated generally by the reference numeral 14) and the work supporting blade by the reference numeral 12, the said rest being secured to a slide 14 for movement along the machine bed, not shown. A feed magazine 16 is rigidly supported by the work rest 10 on suitable bracket means 18. The said' magazine includes a channel-like frame which is disposed atan angle to project upwardly and forwardly of the grinding machine from a position over the work supporting blade l2 which is disposed between the grinding wheel G and the regulatingyvheel R. The channel-like frame of the magazine 16 comprises a-bottom wall 20 and a'pair of side walls 22, 22. In addition to the channel, the magazine 16 includes a top wall strip 24 which issupported in spaced relation ship to the side Walls 22, 22 on brackets 26, 26. The bottom end portion of the magazine 16, including its aforedescribed channel and the spaced top strip 24, is bent or curved downwardly so that the lowermost workpieces W1, W1 in the magazine will be supported'in a substantially horizontal position directly over the top or work-receiving edge of the work supporting blade 12. A magazine 16 of the aforedescribed type is particularly adapted to carry for gravity feed the workpieces W1, W1 each of which has a collar formed thereon between its ends. As shown in Fig. 1, the workpieces are supported in the magazine with their collars engaging the top edges of the side walls 22, 22 of the magazine channel and with the ends of the workpieces disposed adjacent the bottom Wall 20 of the channeland the top strip'24, respectively. Obviously, when workpieces of the aforedescribed general type are supported in the magazine for sliding movement therealong, there' will be gravity biased movement from the forwardly projecting top end of the magazine to the bottom end thereof over the-work supporting blade 12. It will be observed that the said bottom end of the magazine is spaced above the top edge of the Work supporting blade and it will also be observed that the top edge of the blade is provided with a notch 28 to receive the collar on a workpiece and It should also be noted that the specific workpiece W1 shown is to be ground at a portion on one side of the collar and at another portion on the other side thereof. 7

i The means receiving the workpieces W1, W1 at the lower end of the magazine 16 and for feeding them through the grinding throat between the grinding wheel and the regulating wheel to the top of the work supporting blade comprises a rotatable receiver 30 which is supported on a substantially horizontal axis on suitable bushings 32, 32 in a support block 34. The support block 34 is rigidly secured in adjusted position on the work rest 10 as by bracket means indicated generally by the reference numeral 36. The rearwardly projecting portion 38 of the receiver 30 is disposed below the bottom end of the magazine 16 and above the top edge of the work supporting blade 12. The said projecting portion can be formed separately or integrally with the rest of the receiver, but in any event, it is provided in semi-cylindrical form and substantially C shape in transverse cross section. The semi-cylindrical shape is provided to receive and to support the lowermost workpiece W1 in the magazine 16 in nested relationship when the said receiver is in a normal or first rotated position wherein the concave face of the semi-cylindrical portion 38 opens upwardly. In such rotated position of the receiver, the said lowermost workpiece in the magazine is supported above the work supporting blade 12 and its prevents the adjacent workpieces from falling out of the magazine. ceiver 30 is rotated 180 from its said first position, the concave face ofthe rearwardly extending portion of the receiver will be inverted to permit the lowermost workpiece to fall through the grinding throat to the top edge of the work supporting blade 12. However, in being rotated from its first position to its inverted or second position, the semi-cylindrical rearwardly extending portion 38 of the receiver engages the workpiece W1 adjacent the said lowermost workpiece to prevent it and the other workpieces from falling out of the magazine. When the said receiver is returned to its said first rotated position, the said next adjacent workpiece will be received within the semi-cylindrical portion 38 and supported therein. Thus, in oscillating the receiver 30 between its first and second rotated positions, the rearwardly extending por tion 38 thereof will receive and feed the workpieces W1, W1 in sequence. This cycle of operation is made clear in Figs. to 8.

The receiver 30 is rotated or oscillated through 180 by means of a rack 40 which is reciprocable in the receiver support block 34 and which is in engagement with a pinion 42 secured to the front end of the said receiver. The means for reciprocating the rack 40 in the block 34 comprises an air cylinder 44 having a piston (not shown) .which is connected with the feed rack and which is movable in one direction responsive to air under pressure received in the cylinder through an inlet 4-6 in one end thereof, and the piston and rack are movable in the other direction responsive to air under pressure received through an inlet 48 at the other end of the cylinder. As will be described in more detail hereinafter, air flow control means are provided to oscillate the receiver 30 whereby to feed one workpiece W1 each time the regulating wheel R is retracted with respect to the grinding wheel G.

The first embodiment of the work feeding mechanism described above is particularly adapted for use with a centerless grinder having a notched regulating wheel and wherein one workpiece is ground and finished during each revolution of the regulating wheel. That is, the regulating wheel R is of the type having an insert 50 which is adjustable radially of the wheel and which defines a notch 52 at the periphery of the wheel as best shown in Fig. 10. The notch 52 is provided to receive a workpiece W1 after it has been ground and to carry the workpiece away from the grinding throat for ejection. In operation of a centerless grinder having a notched regulating wheel as described, a workpiece must be thrust from the blade 12 into When the rethe notch 52 as the notch is rotated into registry with the top edge of the said blade. At approximately the same time, the regulating wheel R must be retracted with respect to the grinding wheel G to permit the next workpiece to fall upon the top of the work supporting blade 12. Then, the regulating wheel R must be advanced toward the grinding wheel G in the conventional in-fced operation of the grinding machine to grind the workpiece to the required diameter. In the preferred sequence of operation, a workpiece W1 is thrust into the notch 52 when the wheel is rotated to register the notch with the top of the work supporting blade 12, the regulating wheel is retracted with respect to the grinding wheel, a new workpiece is dropped onto the top of the work supporting blade, and the regulating wheel is advanced toward the grinding wheel, all while the regulating wheel R is being rotated. The workpiece is ejected from the notch 52 in a selected rotated position of the regulating wheel R, preferably by a blast of air which thrusts the workpiece out of the notch forwardly or rearwardly of the machine (whichever is preferred) into a hopper or other receptacle provided to receive the finished workpieces.

It has been found desirable to provide means for kicking the finished workpiece from the top of the work supporting blade into the regulating wheel notch. The means for thrusting the workpiece from the blade into the wheel notch may take various forms, the means shown in the drawings being merely exemplary. The said exemplary means for thrusting the workpiece into the regulating wheel notch comprises a bracket 54 which is secured to the work rest 10 and which supports a shaft 56 on a substantially horizontal axis over the grinding throat. A generally arcuate kick-off arm 58 is secured to the shaft 56 and extends downwardly therefrom, the lower end of the said arm being disposed adjacent the top edge of the work supporting blade 12 for engagement with a workpiece W1 thereon when it is pivoted from its normal full-line position to its broken-line position as shown in Fig. 10. In the normal position of the arm 58, it is disposed in spaced relationship within an annular groove 60 in the grinding wheel G, the said grinding wheel being formed to engage and grind the workpiece W1 on both sides of said annular groove. In the broken-line position of the kick-off arm 58, it engages the workpiece W1 within the notch 28 at the top edge of the work supporting blade 12.

The kick-oft arm is pivoted from its lower position to the kick-off position by pivotal movement of a cam arm '62 which is secured to the rearwardly extending portion of the shaft 56, the said arm extending laterally behind the regulating wheel R. A cam block 64 is adjustably secured to the extending end portion of the arm 62 for engagement by a cam trip 66 supported in a block 68 secured to the rear hub 70 of the regulating wheel R. In rotation of the regulating wheel in the direction indicated by the arrows the cam trip 66 will engage the cam block 64 to thrust the cam arm 62 upwardly or in a counterclockwise direction as viewed in Fig. 10. The counterclockwise pivoting movement of the cam arm 62 and the shaft'56 causes counterclockwise pivoting movement of the kick-off arm 58 from its normal position into engagement with the workpiece W1 to thrust the said workpiece into the notch 52. Obviously, the cam trip support block 68 is secured to the regulating wheel hub 70 in such posi tion to actuate the kickoff arm 58 when the notch 52 is in registry with the top edge of the work supporting blade 12. The cam arm 62 andthe kick-off arm 58 can be returned to normal position by providing a spring 72 connected with the bracket 54 and biasing the arm 62 in a clockwise direction to engage a suitable stop 73 against the hub 70.

The preferred means for controlling flow of air under pressure to the air cylinder 44 for the purpose of reciprocating the rack 40 and oscillating the receiver 30 comprises a valve shown schematically in Fig. 11. The said valve 74 may be provided in specifically difierent form,

wheel.

'5 that shown being merely exemplary. The exemplary valve is disposed within a housing 76 having an inlet 78 which is connectible with a source of air under pressure, a pair of outlets 80, 86) connected to drain, and a pair of passages 82, 82 connected with the air cylinder inlets 46 and 48, respectively. A spring 84 is incorporated in the valve structure to bias the valve toward one position wherein to efiect communication between the pressurized source and the air cylinder inlet 48 which retracts the rack 40 and places the receiver 30 in its aforesaid normal or first position to support the lowermost workpiece W1 as shown in Figs. 3, 4 and 5. At the same time, the valve 74 connects the air cylinderfitting 46 to drain. A solenoid 86 is also incorporated in the valve structure and is connected with a source of energy 88 through a pair of conductors 90 and 92, the solenoid being arranged to shift the valve 74 into a second position when energized. In the said second position of the valve 74, the pressurized source is connected with the air cylinder inlet 46 to thrust the rack 40 outwardly thereby inverting the receiver 31), placing the same in the position shown in Fig. 7. At the same time, the air cylinder fitting 48 is connected to drain.

With the valve construction described, wherein the valve is spring biased to a normal or first position, the receiver 30 is normally retained in its first rotated position wherein to support the lowermost workpiece in the magazine 16, and the receiver is inverted to feed a work- 'piece only when the solenoid 86 is energized by closing a switch 94 between the conductors 90 and 92.

In a centerless grinder embodiment using a notched regulating wheel as described, wherein one workpiece is finished in each revolution of the regulating wheel, it is convenient to provide means for automatically closing the valve switch 94 during each revolution of the regulating Such means can comprise a tripping cam 96 (Figs. 9, and 11) which is secured to the front hub of the regulating wheel to engage and close the switch 94 in the rotated position of the regulating wheel wherein a finished workpiece has just been received in the regulating wheel notch and wherein the regulating wheel is about to be retracted. Preferably, the switch 94 is so arranged as to connect a pair of conductors L1 and L2 to complete a circuit to electrically operable means (not shown) which is energized to retract the regulating wheel relative to the grinding wheel.

It is also convenient in operation with a notched regulating wheel to actuate the pneumatic workpiece ejector in a selected rotated position of the regulating wheel by the same or a generally similar cam trip 96. That is, the said pneumatic ejector may comprise a nozzle 98 secured in a selected position on the grinding machine to register with the regulating wheel notch 52 in a selected rotated position thereof and either forwardly or rearwardly of the regulating wheel to blow the finished workpiece W1 from the notch into a hopper or other means such as indicated by the reference numeral 100 (Fig. 11) provided to receive the finished workpieces. An air line 102 connected with the nozzle 98 is also connected with a conduit 104 at a normally closed valve 106. The conduit 104 is connectible with a source of pressure and the valve 106 is opened by a solenoid 188 in the rotated position of the regulating wheel R wherein the wheel notch 52 registers with the nozzle 98. The solenoid is connected with a suitable source of energy 118 through conductors 112 and 114 which are closed by a switch 116 when the tripping cam 96 or its equivalent engages the said switch 116.

The second or alternative form of the work feeding mechanism provided in accordance with this invention is very similar to the first described embodiment, differing therefrom only in details of construction which particularly adapt the mechanism for use. with a conventional regulating wheel (which is not notched) and which par- "6 ticularly adapt the mechanism to eject the finished'workpiece with a plunger.

As in the first described embodiment, the work feeding mechanism includes an elongated magazine 120 which is supported on suitable bracket means 122 secured to a work rest 124 which also mounts a work supporting blade 126. The work rest 124 is secured to a slide 128 for movement therewith. While the magazine 120 is gen erally similar to the first described magazine 16, it projects from a position over the work supporting blade rearwardly and upwardly rather than forwardly and upwardly. The magazine 120 is also different from the first described magazine in that it is particularly adapted to carry and feed by gravity workpieces W2, W2 which are substantially cylindrical and have'a head at one end, the workpieces being arranged and fed in the magazine so that the heads of the workpieces will extend forwardly at the bottom end of the magazine.

Also as in the first described embodiment, the work feeding mechanism includes a rotatable or oscillatable receiver 134 which is supported on a substantially horizontal axis in suitable bearings 132, 132 within a support block 134. The support block is mounted on the work rest 12 4 by suitable bracket means 136 rearwardly of the work supporting blade 126. A forwardly projecting portion 138 of the receiver is provided in semi-cylin drical form to receive the lowermost workpiece W2 (as best shown in Figs. 14 and 15) in a normal or first rotated position of the receiver 130 and to drop the said lowermost workpiece onto the top of the blade 126 in a second rotated position (as shown in Fig. 17) which is approximately 180 from the first position. Thus, the receiver 1363 supports the workpieces within the magazine over the work supporting blade and feeds them one at a time onto the blade in the grinding throat between the regulating wheel and the grinding wheel which are identified as R1 and G1, respectively.

Similarly to the first described embodiment, the air cylinder 44 is mounted on the block 134 to reciprocate the rack 41 therein which engages a pinion 142 secured to the rear end of the receiver 130. Thus, in reciprocation of the rack 40 by the air cylinder 44, the receiver 130 is oscillated through 180 on its axis to feed the workpieces W2, W2 in sequence as illustrated by Figs. 15-18.

The alternative form of construction in addition to using the same rack and air cylinder 40 and 44, utilizes the same pneumatic and electrical control system therefor as shown in Fig. 10. That is, the air cylinder and piston in the alternative form of construction can be operated by the same valve 74 as employed in the similar system and can utilize the same valve solenoid '86. However, since in the alternative form of construction, a conventional, non-notched regulating wheel R1 is employed, and since a workpiece is not necessarily finished in each revolution of the regulating wheel, different means can be employed for closing the switch 94 in the valve solenoid circuit. The preferred means employed for closing the switch 94 comprises a timer shown schematically in Fig. 19. The timer 158 can be arranged as shown to close the switch 94 periodically thereby to energize the solenoid 86 and operate the valve 74 so as to invert the receiver 130 and feed a workpiece W2 onto the blade 126. At all other times the solenoid switch 94 is open and the receiver is in its normal position. With the receiver in its normal position, the timer may be utilized to actuate switch means for retracting and advancing the regulating wheel R1 in the grinding operation, and the timer may be employed to actuate switch means controlling a work ejector as will now be described.

The work ejector, as best shown in Fig. 12, comprises a plunger 152 which is supported in a substantially horizontal position in the support block 134 for movement forwardly thereof into engagement with a workpiece W2 supported on the blade 126. When thrust forwardly as described, the plunger 152 will thrust the workpiece W2 from the work supporting blade 126 forwardly into a hopper 154 or other means provided to receive finished workpieces. The means for operating the plunger 152 preferably comprises an air cylinder 156 having a doubleacting piston (not shown) therein and having two air conduit fittings 158 and 160. The piston is connected with the plunger 152 and is so arranged that when air under pressure is introduced to the cylinder 156 through the fitting 158, the piston and plunger are thrust forwardly to eject a workpiece. When air under pressure is introduced to the cylinder 156 through the fitting 160, the piston and plunger are retracted to the full-line position shown in Fig. 12.

The pneumatic and electrical control system for operating the air cylinder 156 can be identical with the pneumatic and electrical control means provided for operation of the air-cylinder 44. That is, the same type of valve may be used as the valve 74 and the same type of solenoid may be used as the solenoid 86 and the same type of electric circuit can be employed. This similarity of elements is shown in Fig. 19 wherein the valve and electrical elements operating the ejector air cylinder are identified by the same reference characters, but with the suffix a, as their counterparts in the control system for the work feeding cylinder 44. In this connection, it should be noted that the timer 150 is arranged to close the switch 94a and thereby to cause a workpiece W2 to be ejected before the switch 94 is closed to cause the next workpiece W2 to be fed into the operating position.

The invention claimed is:

l. Mechanism for feeding workpieces in sequence during in-feed operation of a centerless grinder of the type having a grinding wheel and a regulating wheel movable toward and away from the grinding wheel and also having a work supporting blade disposed between the grinding wheel and the regulating wheel, the said mechanism comprising a magazine supported over the blade and adapted to carry a plurality of workpieces for gravity feed toward the blade and with the lowermost of the said workpieces disposed substantially horizontally, a receiver disposed between the magazine and the blade and having a substantially horizontal semi-cylindrical portion disposed in a normal rotated position of the receiver to receive the lowermost workpiece and thereby to retain the other workpieces in the magazine, support means for the receiver accommodating rotation thereof between its aforesaid normal position and a second position wherein said semi-cylindrical portion is inverted to release the lowermost workpiece permitting it to fall into operating position on the blade and wherein the semi-cylindrical portion engages the next adjacent workpiece to retain the said other workpieces in the magazine, operating means engaging said receiver to rotate the same between its said normal and second positions, and electrical control means for actuating the operating means to rotate the receiver from its normal position to its second position when the regulating wheel is retracted with respect to the grinding wheel.

2. Mechanism for feeding workpieces in sequence during in-feed operation of a centerless grinder of the type having a grinding wheel and a regulating wheel movable toward and away from the grinding wheel and also having a work supporting blade disposed between the grinding wheel and the regulating wheel, the said mechanism comprising a magazine supported over the blade and adapted to carry a plurality of workpieces for gravity feed toward the blade and with the lowermost of the said workpieces disposed substantially horizontally, a receiver disposed between the magazine and the blade and having a substantially horizontal semi-cylindrical portion disposed in a normal rotated position of the receiver to receive the lowermost workpiece and thereby to retain the other workpieces in the magazine, support means for the receiver accommodating rotation thereof between its aforesaid amass normal position and a second position wherein said semicylindrical portion is inverted to release the lowermost "and electrical control means for actuating the rack to rotate the receiver from its normal position to its second position when the regulating wheel is retracted with respect to the grinding wheel.

3. Mechanism for feeding workpieces in sequence during in-feed operation of a centerless grinder of the type having a grinding wheel and a regulating wheel movable toward and away from the grinding wheel and also having a work supporting blade disposed between the grinding wheel and the regulating wheel, the said mechanism comprising a magazine supported over the blade and adapted to carry a plurality of workpieces for gravity feed toward the blade and with the lowermost of the said workpieces disposed substantially horizontally, a receiver disposed between the magazine and the blade and having a substantially horizontal semi-cylindrical portion disposed in a normal rotated position of the receiver to receive the lowermost workpiece and thereby to retain the other workpieces in the magazine, support means for the receiver accommodating rotation thereof between its aforesaid normal position and a second position wherein said semicylindrical portion is inverted to release the lowermost workpiece permitting it to fall into operating position on the blade and wherein the semi-cylindrical portion engages the next adjacent workpiece to retain the said other workpieces in the magazine, a pinion secured to said receiver, a reciprocable rack engaging said pinion to oscillate the receiver between said normal and second positions, an air cylinder having a double-acting piston secured to said rack for reciprocating the same, a valve connected with said air cylinder and connectible with a source of air under pressure and adapted selectively to control fiow to said cylinder whereby to control movement .of said rack, electric valve operating means adapted when energized to effect movement of said receiver from its normal to its second position, and switch means for energizing said valve operating means with retracting movement of the regulating wheel relative to the grinding wheel.

4. Mechanism for feeding workpieces in sequences during in-feed operation of a centerless grinder of the type having a grinding wheel and a regulating wheel movable toward and away from the grinding wheel and also having a work supporting blade disposed between the grinding wheel and the regulating wheel, the said mechanism comprising a magazine supported over the blade and adapted to carry a plurality of workpieces for gravity feed toward the blade and with the lowermost of the said workpieces disposed substantially horizontally, a receiver disposed between the magazine and the blade and having a substantially horizontal semi-cylindrical portion disposed in a normal rotated position of the receiver to receive the lowermost workpiece and thereby to retain the other workpieces in the magazine, support means for the receiver accommodating rotation thereof between its aforesaid normal position and a second position wherein said semicylindrical portion is inverted to release the lowermost workpiece permitting it to fall into operating position on the blade and wherein the semi-cylindrical portion engages the next adjacent workpiece to retain the said other workpieces in the magazine, operating means engaging said receiver to rotate the same between its said normal and second positions, an ejector carried by said support means for movement into and out of engagement with a workpiece on said blade to eject a workpiece therefrom, operating means for said ejector, and electrical control means for actuating said ejector operating means and for actuating the receiver operating means to rotate the receiver from its normal position to its second position after a workpiece has been ejected from said blade and when the regulating wheel is retracted with respect to the grinding wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,814,363 Booth July 14, 1931 10 Berger et al Feb. 23, 1943 Dahlstrom Apr. 13, 1948 Cramer Oct. 17, 1950 Hill May 20, 1952 FOREIGN PATENTS Great Britain Oct. 11, 1950 

